Spontaneously not accelerating
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New User
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Spontaneously not accelerating
My 2003 Excursion will out of nowhere stop accelerating. If I floor the pedal down it will eventually go. Has anyone experienced this? Also I'm not sure if it's related but sometimes it won't shift gears. The RPM gauge goes up but it doesn't shift. My husband says it's the injectors but from googling that doesn't seem to be a good fit. Any info is appreciated!
Fleet Mechanic
Joined: Nov 2016
Posts: 1,343
Likes: 94
Almost all diagnostics begins by looking at engine parameters and diagnostic trouble codes. These can be obtained through smart apps like Forscan and a wireless adapter that plugs into the obd2 port. Perhaps $40-$50.
Then the world of diagnostics is your oyster. Lots of discussions on this topic, you can search for popular adapters that work with your smart devices.
Let us know when you acquire these. Codes are the first thing to look for.
Then the world of diagnostics is your oyster. Lots of discussions on this topic, you can search for popular adapters that work with your smart devices.
Let us know when you acquire these. Codes are the first thing to look for.
Logistics Pro
Joined: Jul 2014
Posts: 4,673
Likes: 532
From: Houston, Texas
Hmm, that's unusual from the behaviors you describe. Can you confirm that he's using Forscan and not one of the many other products out there? Some are not as good at catching codes for our trucks.
Understand that "describing" a symptom is very little help with modern diesel engines. What you've described could be caused by many different things. For example, it sounds like the way my truck acted when the transmission went into limp mode because one of the harnesses shorted out. None of the other scanners caught the transmission codes. I downloaded Forscan, found the code, identified the harness problem, and fixed it for $100 and an easy hour's work.
Of course, there are problems that don't throw codes, and they're often harder to diagnose. You need an app like Forscan to read data, and possibly a voltmeter to check wires and connectors. Most of the guys here at this point would make dang sure there weren't codes.
Understand that "describing" a symptom is very little help with modern diesel engines. What you've described could be caused by many different things. For example, it sounds like the way my truck acted when the transmission went into limp mode because one of the harnesses shorted out. None of the other scanners caught the transmission codes. I downloaded Forscan, found the code, identified the harness problem, and fixed it for $100 and an easy hour's work.
Of course, there are problems that don't throw codes, and they're often harder to diagnose. You need an app like Forscan to read data, and possibly a voltmeter to check wires and connectors. Most of the guys here at this point would make dang sure there weren't codes.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,652
Likes: 79
From: Mooresville, NC
OP - the situation you're describing is not uncommon (have seen it before, multiple possibilities)
I suspect trans health (but that's a guess at this point) -- I'd:
(1) Run a power balance / cyl contribution to first ascertain integrity
(2) Use an advanced scanner to diagnose the trans
I suspect trans health (but that's a guess at this point) -- I'd:
(1) Run a power balance / cyl contribution to first ascertain integrity
(2) Use an advanced scanner to diagnose the trans
Logistics Pro
Joined: Jul 2014
Posts: 4,673
Likes: 532
From: Houston, Texas
I understand that folks come here desperate for help. That's how I came here years ago. I've come to learn how hard it is to help people here. Guys dedicate hours of their lives doing it, when they could be getting paid $100/hr to do the work. So, we try to do both - help those smarter guys work with you through the correct diagnostic process, and throw some ideas/guesses because we know what it's like sitting there with a broke truck. But, I think we're all mindful of wasting your money too. These trucks are a good value, if you manage your costs. That said...
You could test the transmission theory, kinda, by trying to manually shift, starting in the lowest gear. Take off slowly, and before it would naturally shift into second, shift into second manually. If you were already in second (limp mode), it won't change gears. DISCLAIMER: or something like that. I'm not a transmission expert and we're just guessing at this point. But just check that you have all your gears. If you had Forscan, it will tell you what gear you're in.
You could test the transmission theory, kinda, by trying to manually shift, starting in the lowest gear. Take off slowly, and before it would naturally shift into second, shift into second manually. If you were already in second (limp mode), it won't change gears. DISCLAIMER: or something like that. I'm not a transmission expert and we're just guessing at this point. But just check that you have all your gears. If you had Forscan, it will tell you what gear you're in.
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New User
Joined: Jun 2021
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Adapter
I really appreciate all the help. I've had this car for over 11 years but up until recently, it was mainly a backup. Now that it's my main family car I need to invest in stuff to get through the issues. I downloaded the app and searched amazon for adapters but many pull up. Is there one that's most recommend for the 6.0 diesel?
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New User
Joined: Jun 2021
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Thanks!
I ordered it!
Assuming you have a droid device, this is the one I've not seen complaints on and has been regularly recommended:
https://www.amazon.com/BAFX-Products.../dp/B005NLQAHS
https://www.amazon.com/BAFX-Products.../dp/B005NLQAHS
Thread Starter
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New User
Joined: Jun 2021
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Awesome
Assuming you have a droid device, this is the one I've not seen complaints on and has been regularly recommended:
https://www.amazon.com/BAFX-Products.../dp/B005NLQAHS
https://www.amazon.com/BAFX-Products.../dp/B005NLQAHS
Fleet Owner
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
Seems everyone has missed one very common cause. Loss of the 5 volt Vref will take out the accelerator signal.
Pop the hood and take a look at the EBP plug and make sure that the wires are all in good shape. We had a guy
here that replaced the in cab wiring and other things like the accelerator and never checked the Vref. You can guess
what the issue was I bet. The EBP wiring was damaged and Vref was dropping out. The other places that Vref is used
is the ICP and the MAF sensor just to name a few.
When you get the OBD2 device start by reading codes and watching the Vref. You can also read the three sensors in
the accelerator module.
Post back what you find for codes and if you have a stable Vref. Vref is a 5 VDC signal give or take a tiny bit.
Pop the hood and take a look at the EBP plug and make sure that the wires are all in good shape. We had a guy
here that replaced the in cab wiring and other things like the accelerator and never checked the Vref. You can guess
what the issue was I bet. The EBP wiring was damaged and Vref was dropping out. The other places that Vref is used
is the ICP and the MAF sensor just to name a few.
When you get the OBD2 device start by reading codes and watching the Vref. You can also read the three sensors in
the accelerator module.
Post back what you find for codes and if you have a stable Vref. Vref is a 5 VDC signal give or take a tiny bit.
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